Embodiments of the present invention generally relate to telecommunications and more specifically to techniques for rerouting of communications when connectivity to a central communication processor is lost.
A central office exchange service (Centrex) is a service offered by local telephone companies in which phone facilities at the phone companies' central (local) office are offered to users. For example, the Centrex service allows centralized services to be provided for business companies. The Centrex services may be similar to those provided by a private branch exchange (PBX) service, which is owned by a business entity, and provides services to users in the business entity. The Centrex, which may be referred to by different names in different locations, provides users in a business entity with as much if not more control over the services that are offered by a PBX system.
Calls from a user of the business entity are typically routed through the Centrex. In a Voice over IP network using SIP, these calls typically are routed through a wide area network (WAN) that is external to the business entity. For example, the wide area network may include a network from a business office to another location, such as a central office or another office. The wide area network may be unreliable and connectivity may be lost with the Centrex. Further, the Centrex may not be functioning or may crash. If connectivity to the Centrex is lost, then the users of the business entity may not be able to communicate with other users. For example, a user may not be able to make a telephone call to any other users because the telephone call needs to be routed to the Centrex in order to be routed to its destination. Thus, even calls to users in the same office building cannot be made. Accordingly, the business entity will experience downtime for the telephone system if connectivity to the Centrex is lost.